September 9: ORD

Today is September 9th. It's the 252nd day of the year. 113 days remain. It's week 36 of the year.

Unless noted, the following data is based upon observations collected by the National Weather Service, Chicago, at O'Hare International Airport (ORD) between November 1978 and last year. ORD has been the official site of record for Chicago since Thursday, January 17, 1980.

According to the National Climatic Data Center (NCDC), the normal high is 76 and the normal low is 56. I've calculated the 31-year averages at 78 and 58.

On the hot side, in 1983 the high was the record high of 95 with a low of 70. In 1991 the high was 94 with a low of 70. In 2002 the high was 90 with a low of 66. The record warmest low of 75 occurred way back in 1912, a time when the thermometer was located adjacent to Lake Michigan. Over the last 31 years, 25 highs (81%) were: 70s (15) and 80s (10). Three highs were in the warmer 90s. Three highs were in the cooler 60s.

In looking back through the years to the first September at O'Hare in 1959, the following instances were notable: in 1978 the high was a hot 93 with a low of 65, a hot day. In 1971 the high was 90 with a low of 69, a hot day. In 1966 the high was 82 with a low of 45, a 37 degree spread. In 1965 the high was a hot 88. In 1964 the high was a hot 94 with a low of 62, a 32 degree spread and hot day. In 1963 the high was 85 with a low of 54, a 31 degree spread. In 1961 the high was a hot 89. In 1959 the high was a hot 90 with a low of 65, a hot day.

More recently, there were large spreads of 34 degrees in 1982 (81/47), 31 degrees in 1988 (81/50), 30 degrees in 1981 (75/45) and 30 degrees in 1986 (73/43). There was a small spread of seven degrees in 2006 (70/63).

On the cool side, there were no days of a mean of at least 11.5 degrees below normal. The coolest low was the record low of 43, set in 1986. There were also five other lows in the 40s, the coolest of these being 45 in 1981. The coolest highs were the three in the 60s: 67 in 1992, 69 in 1995 and 69 two years ago. The record coolest high of 56 occurred way back in 1883, a time when the thermometer was located adjacent to Lake Michigan. Over the last 31 years, 23 lows (74%) were: 50s (11) and 60s (12). Six lows were in the cooler 40s and two were in the warmer 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:59 and sunrise is at 6:27. Sunset is at 19:13 and twilight ends at 19:42. There's a total of 12 hours, 46 minutes of daylight today and 13 hours, 43 minutes between twilights. We are losing two or three minutes of daylight a day. Tomorrow twilight begins at 6:00 and sunrise is at 6:28. The moon is waxing crescent, having passed the new phase yesterday morning at 5:30. Illumination was 1% at midnight, will be 3% at noon and 5% at midnight tonight. Moonrise is at 8:02 this morning. Moonset is at 19:33 tonight and moonrise is at 9:20 tomorrow morning. Moonlight time is 11 hours, 31 minutes which is 49 minutes shorter than yesterday.

Patriot Day is in two days and Grandparent's Day is in three days. -Bernie-